Nanosecond Two-Photon Absorption and Lasing in Fluorene-Based Organic Semiconductors

This work reports the nanosecond nonlinear absorption properties of two fluorene-based organic semiconductors and their application in nanosecond two-photon pumped lasers. The materials studied under nanosecond excitation are a first generation bisfluorene-cored dendrimer with biphenyl dendrons, and 2-ethylhexyloxy surface groups and poly(9,9-di-n-octylfluorene). The nonlinear absorption properties are reported, together with tunable distributed feedback lasers that operate under nanosecond two-photon excitation at 600 nm for the dendrimer and 650 nm for the polymer. This highlights the feasibility of optically pumping organic lasers using long excitation pulses in the red part of the spectrum.